Gunfire erupted inside a packed nightclub in Cincinnati, Ohio, early on Sunday morning, killing one person and injuring 16 others.
At least one shooter was still at large hours after the mayhem, authorities said.
The motive behind the shooting was unclear, but Cincinnati assistant police chief Paul Neudigate said on Twitter that “there are no indications this incident is terrorism-related”.
Update: Cameo Night Club 15 gun shot victims, 1 deceased. Homicide unit and all available resources are being utilized. Next update after 11
— Cincinnati Police (@CincyPD) March 26, 2017
“The conflict is believed to have begun between specific groups or individuals earlier in the day, escalating and ultimately leading to this tragedy occurring at the nightclub,” city manager Harry Black said in a statement.
The shooting took place at about 2am local time, as hundreds of people partied inside the Cameo Nightlife club, which Black said has a history of gun violence, including two shootings in the parking lot in 2015.
“At this point it‘s unclear exactly what instigated the shooting,“ Capt Kimberly Williams said at a televised briefing.
“Just a lot of chaos when the shots went off.”
The shooting came less than a year after a gunman opened fire at a gay nightclub in Orlando, Florida, killing 49 people.
It was the deadliest mass shooting in US history.
Cincinnati police initially said they believed at least two shooters were involved in the Cameo incident, but later Mr Neudigate said on Twitter there was only one reported gunman, though police were still trying to determine if there were others.
Hours after the shooting, the suspect was still at large, and police did not have a good description, in part because witnesses were reluctant to co-operate, Williams told WCPO television.
Ohio governor John Kasich sent his condolences and said he had offered state help in the case.
“Saddened to learn about last night’s shooting in Cincinnati,” Mr Kasich said on Twitter.
“Our prayers are with the victims and families of all of those involved.”
Hospital treatment
Eight people from the nightclub were admitted to the University of Cincinnati Medical Centre, a spokeswoman said, with one of them in a critical condition.
Two others were admitted to Christ Hospital, both with minor injuries, while others were treated elsewhere and released.
Cameo Nightlife, a large single-storey structure, is an 11km drive from downtown Cincinnati near the southeast corner of the city, at the heart of the second largest metropolitan area in Ohio with more than 2 million residents.
Reuters